Expression for UDT Instance Documentation from Subfolders

I’m trying to reference the documentation of a UDT instance (UDTInstance.Documentation) in a UDT tag expression (ultimately in an alarm label binding)

Getting the documentation from a flat structure is easy using [.].Documentation

How do you get it using a relative reference if there are folders involved?

I’ve tried the following without success:


The documentation on this doesn’t seem to cover this use case, or I’m not seeing it.

What is the correct relative reference for this?

To reference the Documentation of the ‘DocTopLevel’ tag in the Expression of the ‘DocDeep’ tag, try setting the Expression to ‘{[.]…/…/DocTopLevel.Documentation}’.

I’m trying to reference the documentation of the UDT instance, not of the child member.

I.e. TestDocs.Documentation

Understood, I am able reference the Documentation of the UDT Instance by specifying the tag path to the UDT instance in the Expression. For instance: ‘{[~]TestDocs.Documentation}’.

This is not a solution as it refers to the UDT instance name and relies on the fact that the UDT instance is in the root of the tag provider.

What I require is an relative refers in the UDT definition, 2 folders deep that references the UDT instance documentation, regardless of what the where the UDT is instantiated or what it is called.

I have not found a way to get this to work using relative tag path syntax. However, you can try building a dynamic tag path to the Documentation property of the UDT instance and using the ‘tag’ Expression function to read the value of the property. For example: 'tag(concat({ParentInstanceName}, “.Documentation”)).